在呼吸调节下阻断家兔自主神经对心率的影响研究

Influence of autonomic nerve block on rabbits' heart rate under respiratory regulation

目的观察呼吸频率和潮气量变化对心率的影响。方法建立兔机械通气模型,通过呼吸机调节呼吸参数,在全身麻醉下行呼吸机机械通气。参数调节:潮气量恒定10 m L/kg,呼吸频率40、50、60次/min;呼吸频率恒定50次/min,潮气量8、10、12 m L/kg。动物分组:健康日本大耳白兔72只,其中药物阻滞组30只,分为单纯呼吸组、阿托品组和艾司洛尔组,每组10只;手术切断组42只,分为迷走神经组和交感神经组,每组21只。结果 1药物阻滞组中,3个组在呼吸频率40次/min时的心率,要低于呼吸频率50、60次/min时的心率,差异有统计学意义(P<0.01)。2手术切断组中,迷走组和交感组无论在自主神经分离前还是在切断自主神经后,呼吸频率40次/min时的心率,要低于呼吸频率50、60次/min时的心率,差异有统计学意义(P<0.01,P<0.05)。3药物阻滞组中,3个组在潮气量8 m L/kg时的心率,要低于10、12 m L/kg的心率,差异有统计学意义(P<0.01)。4手术切断组中,迷走组和交感组无论在自主神经分离前还是在切断自主神经后,在潮气量8 m L/kg时的心率,要低于10、12m L/kg的心率,差异有统计学意义(P<0.01,P<0.05)。结论减慢呼吸频率时与心率减慢一致,与HRV频谱成分理论意义相符。无论在正常情况下还是自主神经被阻滞或切断,减少通气量时与心率减慢一致,还需要进一步的研究。

Objective To observe effects of the changes of respiratory frequency （ RF） and tidal volume on rabbits＇heart rate .Methods Mechanical ventilation model was constructed for rabbits and mechanical ventilation was performed under general anesthesia , with respiratory parameters reg-ulated by breathing machine .Respiratory parameters regulation：（ i） the tidal volume was constant at 10 mL/kg while respiratory frequency was set 40, 50, and 60 beats/min separately;（ii） The re-spiratory frequency was constant at 50 beats/min while tidal volume was set 8, 10, and 12 mL/kg separately .Experimental animal grouping：72 healthy rabbits were divided into two major groups , medicine group（30 rabbits） and operation group （42 rabbits）.The former was divided into three subgroups（no medicine, atropine, esmolol） further, each with 10 rabbits.The latter was divided into two subgroups （ pneumogastric nerve and sympathetic nerve ） further, each with 21 rabbits .Re-sults （ i） In medicine group , the heart rates of rabbits in all the three subgroups at a RF of 40 beats/min were significantly lower than those at a RF of 50 or 60 beats/min, and the differences were statistically significant（P〈0.01）.（ii） In operation group, when RF was 40 beats/min, the heart rates of rabbits in pneumogastric nerve subgroup and sympathetic nerve subgroup were signifi -cantly lower than those at a RF of 50 or 60 beats/min, no matter before or after separation of auto-nomic nerve, and the differences were statistically significant （P〈0.01, P〈0.05）.（iii） In medi-cine group, when tidal volume was 8 mL/kg, the heart rates of rabbits in the three subgroups were all lower than those when tidal volume was 10 or 12 mL/kg, and the differences were statistically significant（P〈0.01）.（iv） In operation group, when tidal volume was 8 mL/kg, the heart rates of rabbits in pneumogastric nerve subgroup and sympathetic nerve subgroup were significantly lower than those when tidal volume was 10 or 12 mL/kg, no matter before or after separation of autonomic nerve, and the differences were statistically significant （P〈0.01,P〈0.05）.Conclusion The slowdown of respiratory rate is in accordance with the slowdown of heart rate , which is in line with the HRV spectral composition theory .No matter when it is under normal condition or when automatic nervous system is blocked （ both by medicine and by operation ） , the decrease of tidal volume is in correspondence with the slowdown of heart rate .However the reasons for that requires further investigation.